Question
A circular park has an inner radius of 28 metres. A
track of width 7 metres surrounds the park. Find the cost of levelling the track at the rate of Rs. 3 per square metre.Solution
Outer radius = 28 + 7 = 35 metres Area of outer circle = π × 35²
= (22/7) × 1225
= 3850 m² Area of inner circle = π × 28²
= (22/7) × 784
= 2464 m² Area of the track = 3850 − 2464
= 1386 m² Therefore, cost of levelling the track = 1386 × 3
= Rs. 4158
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